More from WebMD

Dec. 27, 2010 -- Teenage girls now have as much noise-induced hearing loss as teenage boys, an analysis of U.S. data shows.

From 1988 to 1994, hearing tests showed that 18.5% of teens had significant hearing loss by age 19. In 2005-2008, the hearing loss rate among 16- to 19-year-olds dropped to 17.7%, despite a large increase in the percentage of teens "listening to music with headphones" -- likely spurred by use of personal MP3 players.

But while teen hearing loss decreased slightly among boys, it increased by more than 5% in girls. As of 2005-2008, 16.7% of girls and 17.7% of boys had hearing loss by age 19.

This could mean that kids are simply listening to music at safe volumes, note study researchers Elisabeth Henderson and colleagues at Harvard University.

On the other hand, it might not.

Noise causes hearing loss by damaging the sensory hairs inside the cochlea of the ear. It's a cumulative process, and depends not just on noise volume but on how long a person is exposed to damaging levels of noise. And some people are much more vulnerable to noise-induced hearing loss.

So the damage from listening to loud MP3 players for long periods of time might not show up right away.

"The accumulated effects of exposure [to too-loud music] may cause hearing deficits eventually," Henderson and colleagues suggest. "Noise-induced damage might not be evident by 12 to 19 years of age, but might become increasingly evident in the mid-20s."

Henderson and colleagues report their findings in the January issue of Pediatrics.